The present invention relates to removing underground piping and more particularly to replacing deteriorating underground gas piping with new piping. The invention is of particular utility in removing deteriorating steel pipe lines used to provide gas service from the street mains into an adjacent building.
Heretofore, replacing local gas lines required excavating a trench from the building out to the main, a costly operation causing disruption of walkways and roadways. The lines require replacement as a consequence of deterioration through corrosion. The current practice is to replace the steel pipe sections with plastic piping.
Several companies produce pneumatic tools with various adapter heads for boring passages under pavements and the like to minimize the amount of trench excavating required. The known pneumatic tools are constructed to either drive a pipe before it or trail a pipe behind it as it bores a passage before it. These pneumatic tools are variously identified as "boring tools" or "piercing tools", and the like. They have also been called "missiles", "moles" and "rams". The term "pneumatic ram" will be used in the following disclosure to encompass all of such tools. As far as is known, such tools have never been adapted and used to drive an already installed pipe out from its embedment.